Apple on their own web site feature the iPad for Post-critical care. That is in educating the patient about what to do to recover. This is an interesting choice of application, as it avoids most of the issues to do with reliability, performance and security, which apply to medical records applications. The iPad would be used essentially as a fancy flip chart to show the patient diagrams. So it does not much matter if it breaks and it would not need to hold sensitive medical records.
If the iPad works okay in training, as I expect it will, this will create a demand for tablet computers to be used throughout medicine. There have been attempts at using tablet computers previously in hospitals, but these have tended to be large, heavy devices with cumbersome software. The iPad might be what makes e-heath popular and practical.
The ACT Health Library, provided by the Australian National University, has a list of iPhone/iPad/Mobile medical reference works available. This includes several reference works which require medical staff to register with their corporate identification to gain access. Others are apps for a moderate charge. There are also dozens of free items for medical students and patient education.